Low-voltage driven display devices utilizing a voltage of IkV or less to excite phosphor material include FEDs (field emission displays), VFDs (vacuum fluorescent displays), etc. FEDs utilize well-established cathode-anode-phosphor technology in combination with dot matrix cellular construction of each pixel. VFDs also utilize cathode-anode-phosphor technology; electrons are emitted from a filament, and controlled by a grid electrode and an anode electrode to collide with phosphor material on the anode to excite the phosphor material. Generally, a CRT (cathode ray tube) produces various color images by mixing red, green and blue lights emitted from red, green and blue phosphors, respectively. It is difficult for VFDs or FEDs to radiate various colors by mixing red, green and blue lights because VFDs and FEDs generally only use one color phosphor. To obtain a white color in a VFD or FED, a red filter is generally mounted on a green phosphor. The white ray obtained by such a method does not have enough brightness and its color is not clear. The requirement of an additional filter also results in an increase in the production cost. Thus, with the ever-increasing demand for various color phosphors, there is a need to develop a white phosphor self-emitting a white ray.